/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.iotdb.db.mpp.plan.expression.unary;

import org.apache.iotdb.db.mpp.plan.expression.Expression;
import org.apache.iotdb.db.mpp.plan.expression.ExpressionType;
import org.apache.iotdb.db.mpp.plan.expression.visitor.ExpressionVisitor;
import org.apache.iotdb.tsfile.utils.ReadWriteIOUtils;

import java.io.DataOutputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.regex.Pattern;

public class LikeExpression extends UnaryExpression {

    private final String patternString;
    private final Pattern pattern;

    public LikeExpression(Expression expression, String patternString) {
        super(expression);
        this.patternString = patternString;
        pattern = compile();
    }

    public LikeExpression(Expression expression, String patternString, Pattern pattern) {
        super(expression);
        this.patternString = patternString;
        this.pattern = pattern;
    }

    public LikeExpression(ByteBuffer byteBuffer) {
        super(Expression.deserialize(byteBuffer));
        patternString = ReadWriteIOUtils.readString(byteBuffer);
        pattern = compile();
    }

    public String getPatternString() {
        return patternString;
    }

    public Pattern getPattern() {
        return pattern;
    }

    /**
     * The main idea of this part comes from
     * https://codereview.stackexchange.com/questions/36861/convert-sql-like-to-regex/36864
     */
    private Pattern compile() {
        String unescapeValue = unescapeString(patternString);
        String specialRegexString = ".^$*+?{}[]|()";
        StringBuilder patternBuilder = new StringBuilder();
        patternBuilder.append("^");
        for (int i = 0; i < unescapeValue.length(); i++) {
            String ch = String.valueOf(unescapeValue.charAt(i));
            if (specialRegexString.contains(ch)) {
                ch = "\\" + unescapeValue.charAt(i);
            }
            if (i == 0
                    || !"\\".equals(String.valueOf(unescapeValue.charAt(i - 1)))
                    || i >= 2
                    && "\\\\"
                    .equals(
                            patternBuilder.substring(
                                    patternBuilder.length() - 2, patternBuilder.length()))) {
                patternBuilder.append(ch.replace("%", ".*?").replace("_", "."));
            } else {
                patternBuilder.append(ch);
            }
        }
        patternBuilder.append("$");
        return Pattern.compile(patternBuilder.toString());
    }

    /**
     * This Method is for un-escaping strings except '\' before special string '%', '_', '\', because
     * we need to use '\' to judge whether to replace this to regexp string
     */
    private String unescapeString(String value) {
        StringBuilder stringBuilder = new StringBuilder();
        for (int i = 0; i < value.length(); i++) {
            String ch = String.valueOf(value.charAt(i));
            if ("\\".equals(ch)) {
                if (i < value.length() - 1) {
                    String nextChar = String.valueOf(value.charAt(i + 1));
                    if ("%".equals(nextChar) || "_".equals(nextChar) || "\\".equals(nextChar)) {
                        stringBuilder.append(ch);
                    }
                    if ("\\".equals(nextChar)) {
                        i++;
                    }
                }
            } else {
                stringBuilder.append(ch);
            }
        }
        return stringBuilder.toString();
    }

    @Override
    protected String getExpressionStringInternal() {
        return expression + " LIKE '" + pattern + "'";
    }

    @Override
    public ExpressionType getExpressionType() {
        return ExpressionType.LIKE;
    }

    @Override
    protected Expression constructExpression(Expression childExpression) {
        return new LikeExpression(childExpression, patternString, pattern);
    }

    @Override
    protected void serialize(ByteBuffer byteBuffer) {
        super.serialize(byteBuffer);
        ReadWriteIOUtils.write(patternString, byteBuffer);
    }

    @Override
    protected void serialize(DataOutputStream stream) throws IOException {
        super.serialize(stream);
        ReadWriteIOUtils.write(patternString, stream);
    }

    @Override
    public <R, C> R accept(ExpressionVisitor<R, C> visitor, C context) {
        return visitor.visitLikeExpression(this, context);
    }
}
